A CRT, such as a color television picture tube, which is manufactured by the EPS process, is usually prepared by the steps comprising (a) providing a volatilizable photoreceptor, including a conductive layer with an overlying photoconductive layer, on an interior surface of a faceplate panel; (b) establishing a substantially uniform electrostatic charge on the photoreceptor; (c) exposing selected areas of the photoreceptor to actinic radiation to affect the charge distribution thereon; (d) developing the photoreceptor with at least one dry-powdered, light-emitting, triboelectrically-charged screen structure material; (e) fixing, filming and then aluminizing the screen structure material; and (f) baking the faceplate panel, in air, to drive-off the volatile constituents of the photoreceptor, the screen structure material, and the filming material to form the screen assembly. After this initial baking step, the faceplate panel, with the screen assembly on the interior surface thereof, having a color selection electrode mounted therein, and spaced from the screen assembly, is frit sealed to a funnel to form the CRT envelope.
It is desirable to improve the manufacturing efficiency of the above-described process. It is known, for example, in the conventional screen manufacturing art, where the screen and matrix are formed by the so-called, "wet process" described in U.S. Pat. No. 3,558,310, issued to Mayaud on Jan. 26, 1972, to combine the panel bake-out step with the frit sealing step. Such a combined process is described in U.S. Pat. No. 4,493,668 issued to Piascinski et al. on Jan. 15, 1985 and U.S. Pat. No. 5,145,511 issued to Patel et al. on Sep. 8, 1992. However, in the wet process, the number of volatile screen constituents is less than in the EPS process, because in the wet process the layer of photosensitive material initially deposited on the faceplate panel in the formation of the matrix is partially washed off during a development step, and the remainder of the photosensitive material is removed by an etchant. Thus, the volatilizable constituents of a conventional screen include only the matrix and phosphor screen structure materials and the filming material disposed between the screen structure materials and an aluminum layer. In contrast, an EPS manufactured screen includes a volatilizable, two-layered photoreceptor, matrix material, phosphor materials and a filming resin. Thus, if efficiencies in the manufacturing process are to be achieved, a more readily volatilizable photoreceptor must be provided in order to eliminate the present separate panel baking step.